The streets of north Belfast erupted into violence for the third night running yesterday as a 500 strong mob of loyalists wreaked havoc in the area leading to the Catholic Holy Cross primary school.

Loyalist rioters drove three cars into RUC and army jeeps blocking their access to the nationalist area before setting them alight.

Several blast bombs were thrown as well as a nail bomb, and rounds of automatic gunfire were directed at the riven Ardoyne Road.

The attacks, which began at 7pm and saw at least two officers injured by bombs, were described as "significant rioting" by the RUC ground commander, whose operation forced the loyalists away from the flashpoint area.

The disturbances came after a Protestant teenager was killed by a hit and run driver. In the morning, riot police were needed to hold back loyalists blocking Catholic children getting to school.

An army officer caught the brunt of a pipe bomb, and 20 others were injured, as troops and riot police held back 200 baying loyalists who screamed abuse as the 60 schoolgirls and their parents walked in near silence up the Ardoyne Road.

It was later that Thomas McDonald, 16, a Protestant living in another flashpoint area, was apparently pursued on his bike by a car driven from a Catholic estate and then run over.

A 32-year-old woman was arrested and police launched a murder investigation when the boy died in hospital from serious head wounds.

Despite church leaders calling for an end to the Holy Cross protests, Protestant residents had turned out in force to shout abuse at parents and children entering their section of the Ardoyne Road to walk to school.

Protestant residents said they are being held in a "constant state of siege" by their Catholic neighbours. The Catholics said that they too have come under attack, and are just maintaining their right to walk up the road.

Earlier yesterday, after a night of rioting in which 35 RUC officers were injured amid petrol bomb throwing, garden fencing was used to attack security forces.

Baton-wielding police had stormed into a garden where some 50 loyalists had gathered, and fought as the angry mob pelted them with rocks, fence poles and flowerpots.

A huge blast then erupted as a petrol bomb was thrown, and police forced around 150 loyalists back down the road.

But when the Catholic families began their 400 yard walk through a corridor of RUC and army Land Rovers, the abuse was mainly verbal.

After leaving their children, aged just four to 11, mothers expressed relief at the security arrangements, but several said their children would not return to school until the RUC and army presence was no longer necessary and until the threat from the Red Hand Defenders, a cover name used by loyalist paramilitaries, had been removed.

"This is still threatening because you can still feel the hatred against us", said Philomena Flood, who had left her daughter Erwin, seven, at home. "And my child has been traumatised enough."

The Ulster Unionist leader, David Trimble, warned that the scenes of violence could spread to other schools.

It is understood that the the dead teenager, who rode his bike at another notorious flashpoint in Whitewell Road, was followed by a car from a nationalist estate.

Residents claimed the car chased him into the area, mounted the pavement to hit him, and then reversed over him. A woman was arrested and three others detained.

The accident occurred at a spot where paint bombs and stones were thrown during violent clashes at the spot on Sunday and Monday nights.

Earlier yesterday, Detective Superintendent John Brannigan predicted the possibility of further violence: "It's a tragic incident happening on an interface which has witnessed sectarian strife over recent times and I would obviously appeal for calm and restraint over the incident."

Residents in the loyalist enclave of just 212 Protestant houses, warned there would be recriminations. "It will be an eye for an eye, there is no point in telling lies about it", said Samuel Blair, 45. "We've been under siege for 10 years but those who killed this young lad have upped the ante. Tensions are very, very high."

Nigel Dodds, the Democratic Unionist MP for North Belfast, said: "This incident was tragic for the family but also disastrous for community relations, because it will undoubtedly fuel an extremely volatile situation in that part of north Belfast. I would appeal for calm, but I fear my calls will fall on deaf ears."